So in this practice we must do everything with detachment. How are we to detach? We detach by seeing things clearly. Know the characteristics of the body and mind as they are. We meditate in order to find peace, but in doing so we see that which is not peaceful. This is because movement is the nature of the mind.
When practicing samadhi we fix our attention on the in and out-breaths at the nose tip or the upper lip. This "lifting" the mind to fix it is called vitakka, or "lifting up." When we have thus "lifted" the mind and are fixed on an object, this is called vicara, the contemplation of the breath at the nose tip. This quality of vicara will naturally mingle with other mental sensations, and we may think that our mind is not still, that it won't calm down, but actually this is simply the workings of vicara as it mingles with those sensations. Now if this goes too far in the wrong direction, our mind will lose its collectedness, so then we must set up the mind afresh, lifting it up to the object of concentration with vitakka. As soon as we have thus established our attention vicara takes over, mingling with the various mental sensations.
Now when we see this happening, our lack of understanding may lead us to wonder: "Why has my mind wandered? I wanted it to be still, why isn't it still?" This is practicing with attachment.
Actually the mind is simply following its nature, but we go and add on to that activity by wanting the mind to be still and thinking "Why isn't it still?" Aversion arises and so we add that on to everything else, increasing our doubts, increasing our suffering and increasing our confusion. So if there is vicara, reflecting on the various happenings within the mind in this way, we should wisely consider..."Ah, the mind is simply like this." There, that's the One Who Knows talking, telling you to see things as they are. The mind is simply like this. We let it go at that and the mind becomes peaceful. When it's no longer centered we bring up vitakka once more, and shortly there is clam again. Vitakka and vicara work together like this. We use vicara to contemplate the various sensations which arise. When vicara becomes gradually more scattered we once again "lift" our attention with vitakka.
The important thing here is that our practice at this point must be done with detachment. Seeing the process of vicara interacting with the mental sensations we may think that the mind is confused and become averse to this process. This is the cause right here. We aren't happy simply because we want the mind to be still. This is the cause -- wrong view. If we correct our view just a little, seeing this activity as simply the nature of mind, just this is enough to subdue the confusion. This is called letting go.
Now, if we don't attach, if we practice with "letting go"... detachment within activity and activity within detachment... if we learn to practice like this, then vicara will naturally tend to have less to work with. If our mind ceases to be disturbed, then vicara will incline to contemplating Dhamma, because if we don't contemplate Dhamma the mind returns to distraction.
So there is vitakka then vicara, vitakka then vicara, vitakka then vicara and so on, until vicara becomes gradually more subtle. At first vicara goes all over the place. When we understand this as simply the natural activity of the mind, it won't bother us unless we attach to it. It's like flowing water. If we get obsessed with it, asking "Why does it flow?" then naturally we suffer. If we understand that the water simply flows because that's its nature then there's no suffering. Vicara is like this. There is vitakka, then vicara, interacting with mental sensations. We can take these sensations as our object of meditation, calming the mind by noting those sensations.
If we know the nature of the mind like this then we let go, just like letting the water flow by. Vicara becomes more and more subtle. Perhaps the mind inclines to contemplating the body, or death for instance, or some other theme of Dhamma. When the theme of contemplation is right there will arise a feeling of well-being. What is that well-being? It is piti (rapture). Piti, well-being, arises. It may manifest as goose-pimples, coolness or lightness. The mind is enrapt. This is called piti. There are also pleasures, sukha, the coming and going of various sensations; and the state of ekaggatarammana, or one-pointedness.
Now if we talk in terms of the first stage of concentration it must be like this: vitakka, vicara, piti, sukha, ekaggata. So what is the second stage like? As the mind becomes progressively more subtle, vitakka and vicara become comparatively coarser, so that they are discarded, leaving only piti, sukha, and ekaggata. This is something that the mind does of itself, we don't have to conjecture about it, just to know things as they are.
As the mind becomes more refined, piti is eventually thrown off, leaving only sukha and ekaggata, and so we take note of that. Where does piti go to? It doesn't go anywhere, it's just that the mind becomes increasingly more subtle so that it throws off those qualities that are too coarse for it. Whatever's too coarse it throws out, and it keeps throwing off like this until it reaches the peak of subtlety, known in the books as the Fourth Jhana, the highest level of absorption. Here the mind has progressively discarded whatever becomes too coarse for it, until there remain only ekaggata and upekkha, equanimity. There's nothing further, this is the limit.
When the mind is developing the stages of samadhi it must proceed in this way, but please let us understand the basics of practice. We want to make the mind still but it won't be still. This is practicing out of desire, but we don't realize it. We have the desire for calm. The mind is already disturbed and then we further disturb things by wanting to make it calm. This very wanting is the cause. We don't see that this wanting to calm the mind is tanha (craving). It's just like increasing the burden. The more we desire calm the more disturbed the mind becomes, until we just give up. We end up fighting all the time, sitting and struggling with ourselves.
Why is this? Because we don't reflect back on how we have set up the mind. Know that the conditions of mind are simply the way they are. Whatever arises, just observe it. It is simply the nature of the mind, it isn't harmful unless we don't understand its nature. It's not dangerous if we see its activity for what it is. So we practice with vitakka and vicara until the mind begins to settle down and become less forceful. When sensations arise we contemplate them, we mingle with them and come to know them.
However, usually we tend to start fighting with them, because right from the beginning we're determined to calm the mind. As soon as we sit the thoughts come to bother us. As soon as we set up our meditation object our attention wanders, the mind wanders off after all the thoughts, thinking that those thoughts have come to disturb us, but actually the problem arises right here, from the very wanting.
If we see that the mind is simply behaving according to its nature, that it naturally comes and goes like this, and if we don't get over-interested in it, we can understand its ways as much the same as a child. Children don't know any better, they may say all kinds of things. If we understand them we just let them talk, children naturally talk like that. When we let go like this there is no obsession with the child. We can talk to our guests undisturbed, while the child chatters and plays around. The mind is like this. It's not harmful unless we grab on to it and get obsessed over it. That's the real cause of trouble.
When piti arises one feels an indescribable pleasure, which only those who experience can appreciate. Sukha (pleasure) arises, and there is also the quality of one-pointedness. There are vitakka, vicara, piti, sukha and ekaggata. These five qualities all converge at the one place. Even though they are different qualities they are all collected in the one place, and we can see them all there, just like seeing many different kinds of fruit in the one bowl. Vitakka, vicara, piti, sukha and ekaggata -- we can see them all in the one mind, all five qualities. If one were to ask, "How is there vitakka, how is there vicara, how are there piti and sukha?..." it would be difficult to answer, but when they converge in the mind we will see how it is for ourselves.
At this point our practice becomes somewhat special. We must have recollection and self-awareness and not lose ourselves. Know things for what they are. These are stages of meditation, the potential of the mind. Don't doubt anything with regard to the practice. Even if you sink into the earth or fly into the air, or even "die" while sitting, don't doubt it. Whatever the qualities of the mind are, just stay with the knowing. This is our foundation: to have sati, recollection, and sampajañña, self-awareness, whether standing, walking, sitting, or reclining. Whatever arises, just leave it be, don't cling to it. Be it like or dislike, happiness or suffering, doubt or certainty, contemplate with vicara and gauge the results of those qualities. Don't try to label everything, just know it. See that all the things that arise in the mind are simply sensations. They are transient. They arise, exist and cease. That's all there is to them, they have no self or being, they are neither "us" nor "them." They are not worthy of clinging to, any of them.
http://www.what-buddha-taught.net/Books/Ajahn_Chah_Food_for_the_Heart.htm#samma